The invention relates to a device for reproducing slice images during treatment of an object to be examined, as well as to a medical instrument to be inserted partly into an object to be examined during a treatment. The invention also relates to a corresponding method for forming slice images.
A device and a method of the kind set forth are known from U.S. Pat. No. 5,954,648. Therein, the position of a medical treatment instrument, for example a biopsy needle, is determined by means of an optical position measuring system and reproduced in X-ray slice images pre-operatively formed by means of an X-ray device. To this end, the medical instrument is provided with LEDs whose position in space can be determined by means of a camera of the position measuring system. A suitable registration method can be applied so as to convert such positions in space into positions relative to the imaging geometry of the X-ray device and hence relative to the X-ray slice images.
When use is made of such a device, notably for image-guided surgery, the attending physician is offered one or more slice images in which the instantaneous position of the medical instrument is reproduced so as to facilitate the guiding of the instrument within the object to be examined. The orientation and position of the images shown are fixed at the beginning; for example, each time a slice image is displayed which is situated in a plane whereto the medical instrument extends at right angles and which extends through the tip of the medical instrument. The position of the slice image reproduced is then moved along, for example, with the medical instrument or varied by entry into a control computer. However, it would be attractive if the position and orientation of the slice images reproduced could be adjusted quickly, simply and notably interactively by the attending physician himself or herself, so that the physician can always obtain an impression of the anatomy of the object to be examined itself.
Therefore, it is an object of the invention to modify a device of the kind set forth so as to enable simple, fast and interactive variation of the position and orientation of the slice images reproduced. It is also an object to propose a medical instrument and a method appropriate for said device.
The object for reproducing slice images during treatment of an object to be examined, which device includes measuring means for determining, relative to a reference system, the position of a medical instrument partly inserted into the object to be examined during the treatment, wherein adjusting means are provided on a part of the medical instrument which projects from the object to be examined after its insertion therein, which adjusting means are arranged to change the orientation of the slice images reproduced
The invention is based on the recognition of the fact that appropriate adjusting means for changing the orientation of the slice images reproduced should be arranged in a location where the attending physician can simply and interactively change their adjustment. In the case of an intervention by means of a medical instrument, this location is the medical instrument itself. A change of the adjustment of such adjusting means thus enables direct reproduction of a differently oriented slice, with as little delay as possible. For example, the angle between a slice extending through the tip of the medical instrument and the longitudinal axis of the medical instrument can be varied. Alternatively, a slice extending through the longitudinal axis of the medical instrument can be rotated about the medical instrument. The slice images reproduced themselves can be formed either from a three-dimensional, pre-operatively acquired image data set, acquired by means of a suitable imaging device such as an X-ray device, a computed tomography apparatus, a magnetic resonance tomography apparatus or an ultrasound device, or be acquired intra-operatively by means of such an imaging device during the treatment.
The adjusting means in a further embodiment of the invention are coupled to a control unit, for example via a wired connection or a wireless link, in order to apply the instantaneous adjustment of the adjusting means to the control unit and hence influence the reproduction and possibly previous formation of the slice images.
The adjusting means in an alternative embodiment of the invention are constructed in such a manner that their adjustment can be determined by means of the measuring means. For example, when use is made of a known optical position measuring system, as envisaged in a further embodiment of the invention, the adjusting means may be provided, like a medical instrument itself, with LEDs whose positions in space can be determined, thus enabling adjustment of the adjusting means. Such a position measuring system preferably utilizes infrared LEDs and infrared cameras; however, there are also other possibilities such as electromagnetic receivers and transmitters.
The embodiments of the invention as disclosed in the claims 4 to 6 are intended to enable as simple and easy as possible operation of the adjusting means. Preferably, a value characterizing the orientation of a slice image reproduced, for example the angle between a slice reproduced and a reference slice, should also be readable on the basis of the adjusting means.
The adjusting means include a rotary switch. The rotary switch includes two pins that are arranged in a cross-like arrangement so as to extend perpendicularly to the longitudinal axis of the medical instrument, the pins being rotatable about the longitudinal axis of the medical instrument and indicating the orientation of two slice images reproduced, each of said slice images being situated in a plane defined by the longitudinal axis of the medical instrument and a pin axis extending through a pin adjusting means. Adjusting means of this kind can be simply manufactured, can be readily operated and, if necessary, can be simply provided on and removed from existing medical instruments.
Slice images extending through the longitudinal axis of the medical instrument are reproduced in a preferred embodiment. Such slice images can be rotated about said longitudinal axis by means of the adjusting means.
In a preferred embodiment in which an X-ray device is provided, slice images formed from a pre-operatively acquired image data set as well as intra-operatively formed X-ray slice images or in X-ray projection images can be reproduced. The adjusting means may be constructed in such a manner that the orientation of the intra-operatively formed X-ray images as well as the slice images formed from the pre-operatively acquired image data set can be influenced. The adjusting means are thus also capable of controlling the formation of X-ray images by means of the X-ray device which may be, for example, a C-arm X-ray device.
The adjusting means are constructed so that they can be reproduced in the X-ray images, the measuring means being constructed in such a manner that the adjustment of the adjusting means can be determined from the reproduction of the adjusting means. A separate position measuring system as described above can be dispensed with in such a further embodiment. The position of the medical instrument relative to the pre-operatively acquired image data set and the instantaneous adjustment of the adjusting means are then determined by reproducing at least a part of the medical instrument and the adjusting means in intra-operatively acquired X-ray images, for example X-ray projection images. Using a suitable registration method, the position of the medical instrument is determined from such X-ray images which are formed, for example, at fixed time intervals, during a treatment the adjustment of the adjusting means then being xe2x80x9creadxe2x80x9d. To this end, the adjusting means are preferably constructed and the X-ray images are formed in such a manner that the determination of the adjustment is unambiguously and simply possible, so that such determination can also be performed in a computer-aided fashion.
The invention also covers a medical instrument appropriately configured for use in conjunction with a device according to the invention. The medical instrument is provided notably with suitable adjusting means which may be constructed as described above.